A pulsation damper adopted in a conventional high pressure fuel pump and the like is known (refer for example to Patent Literature 1), wherein a diaphragm disposed in a pressurizing chamber of a housing body absorbs and reduces pulsation of a fluid taken into the pressurizing chamber through an intake passage.
In this type of conventional pulsation damper, the diaphragm is formed by press-working a metal plate formed for example of stainless steel, such that it has a projected portion in one direction and that a ceiling portion (center portion) of the projected portion constitutes a flat surface parallel to a flange on the outer periphery of the diaphragm.
The pulsation damper is configured by performing full-circle welding of the diaphragm to a predetermined flat plate (metal plate), or interposing a flat plate between two diaphragms and performing full-circle welding of the metal plate and the diaphragms, or arranging the two diaphragms to directly face each other without interposing a metal plate, and performing full-circle welding to constitute the pulsation damper.
At this time, inert gas such as helium and nitrogen is sealed as internal gas having a predetermined pressure in a space defined by the diaphragm and the metal plate, or in the space defined by two diaphragms.
Patent Literature 2 discloses an art related to a pulsation damper having two diaphragms arranged on both sides of a plate-like member, wherein an elastic member is arranged in the plate-like member to prevent inner sides of a center portion of the diaphragms from being in contact with the plate-like member if excessive pressure fluctuation (pulsation) occurs and the diaphragms are displaced in a direction approximating each other. According to this technique, even if excessive pressure fluctuation occurs, the diaphragms are prevented from being damaged or subjected to plastic deformation, the reduction of the intrinsic pulsation absorption effect can be prevented, and the deterioration of life of the diaphragms caused by acceleration of fatigue at stress occurrence portions of the diaphragm can be prevented.